Modeling Realistic Dynamics of Nanoparticle Dimers for Magneto-Optical Matter

TL;DR

This paper introduces a numerical framework based on Langevin dynamics to model and analyze the realistic, controllable dynamics of magneto-optical nanoparticle dimers, including effects of thermal noise, collisions, and resonance conditions.

Contribution

It presents a novel, comprehensive simulation approach for magneto-optical nanoparticle systems that accounts for realistic forces, noise, and collision phenomena, advancing understanding of their dynamic binding behavior.

Findings

Stable binding at resonance conditions despite collisions

Thermal noise influences on nanoparticle dynamics

Resonance tuning enables controlled assembly

Abstract

Traditional approaches to optical matter often involve complex illumination fields with costly and unstable setups, requiring strong gradient forces, high-intensity laser spots that could harm samples, and substrate support. For binding, attractive inter-particle forces may not be sufficient to assemble systems due to unbalanced components such as centrifugal forces or collisions. In previous work, magneto-optical nanoparticles illuminated with two counter-propagating circularly polarized waves were optically bound under quasi-static conditions. However, the dynamics of such nano systems were not thoroughly considered. Here, a general framework to study magneto-optical (MO) matter is introduced, controllable by static magnetic fields. Dynamic binding between two n-doped InSb nanoparticles, which exhibit surface plasmons at THz frequencies, is recreated. Additionally, the reported examples may represent a novel approach of low-energy illumination sources without gradient components. This numerical framework, grounded in Langevin dynamics and realistic collision phenomena, serves as a robust and universal tool for exploring various optomechanical designs. The impact of thermal noise, collision types, initial conditions, and resonance excitation on a dimer system is examined. Dimers tuned initially at magneto-optical resonance can bind in stable, average positions even when particle-particle collisions are present. The current methodology provides essential knowledge for studying optical binding and the dynamics of any small-scale cluster of interacting sub-units.